Combine the soy sauce and sweet chili sauce in a heavy duty freezer bag. Add chicken breasts and turn to coat in marinade.
Fridge: Marinate the chicken in the fridge for 2-24 hours.
Freezer: If freezing, place in the freezer immediately. Thaw in the fridge overnight, or by immersing the bag in a bowl of cold water for a couple of hours.
Heat oven to 425°F. Add the chicken and marinade to shallow baking dish. Add water (amounts indicated above) to the marinade and mix with a spoon.
Bake chicken for 10 minutes, flip over, then bake for another 10-20 minutes. For 5-7 oz chicken breasts, bake for 20 minutes total.
For 10 oz and larger chicken breasts, bake for at least 25 minutes.
Allow chicken to rest at room temperature for 5-10 minutes before slicing. Serve with sauce spooned over the chicken.